In the production of storage batteries or the like, wire meshes or grids are necessary for forming the positive and negative plates and the plate assemblies composed of them, it being possible for such grids to consist of materials of many different types, depending on the type of storage battery. Thus, for the manufacture of grids and the positive and negative plates which are formed thereby, other materials than lead or lead alloys have been used. Aluminum and copper, nickel, and iron, as well as nickel and cadmium alloys have, in fact, also been used for this purpose.
However, the manufacture of such wire meshes or grids is complicated and costly. Particularly when they consist of lead or lead alloys, they are in fact produced by an appropriate molding by a casting procedure, or they are even produced by a stamping operation from metal strips or the like. It can also be imagined that the grids could be produced from a plurality of intersecting profiled wires, the said wires being soldered or bonded to one another at their points of intersection. In the latter case, it is also necessary in addition for marginal strips without meshes to be connected at least to the top and the bottom edges of the grid, the said strips not only serving to hold and align the positive and/or negative plates in the casing of the battery, but also being capable of being used to connect the terminal heads.
A process for manufacturing grids to form positive and/or negatives plates for storage batteries or the like is also shown in the U.S. Pat. No. 3,853,626 in which the wire meshes or grids are formed from a metal strip which has two substantially parallel boundary edges, the said grids having a mesh-free strip at least at their top and bottom margins. In accordance with this process, the grids are manufactured in the same manner as expanded metal; that is to say, rows of cut slits are initially formed extending approximately parallel to the boundary edges of a metal strip, the ends of said slits having a fixed spacing from one another. The adjacent rows of such slits are so offset relative to one another in the longitudinal direction that the section of material which remains between those facing ends of two slits which lies on the same line is always disposed at half the length of the slits in the adjacent row. Thereafter, the bars of material which are left alongside the separately cut slits are deformed transversely of their longitudinal direction by a suitable tool, so that diamond-shaped mesh openings are formed between them. Using this type of process, therefore, the bars which define the individual meshes are stretched and, as a result, the crystalline structure thereof is modified. Using this procedure, it is the nodal points or junctions which are particularly stressed and from which in each case four mesh bars extend.
It is also disadvantageous in such case that the bars defining the individual meshes relatively to one another extend at an angle of inclination relative to the mesh-free strips which are provided on the upper and lower margins of the grid, so that the voltage potential set up in the positive and negative plate can never be discharged rectilinearly along the shortest path to the mesh-free marginal strip.
It is, therefore, an object of the invention to eliminate all disadvantages attached to the known grids for forming positive and negative plates for storage batteries or the like; it is, accordingly, a purpose of the invention to indicate a process for the manufacture of grids for forming positive and negative plates for storage batteries or the like from a metal strip or the like having two substantially parallel boundary edges and mesh-free strips limiting the grid (at least at the top and bottom margins thereof) wherein an expansion stress on the crosspieces or bars defining the meshes is avoided and, hence, a change in the crystalline structure of the material is avoided; the process makes it possible to provide grids in which one group of mesh bars extends parallel to the mesh-free strips on the margins and the other group of mesh bars extends at right angles to the said strips.